import './index.less'
import React, { Component } from 'react'

export default class Count extends Component {
    increment = () => {
        const {value} = this.selectNumber;
        const {count} = this.state;
        this.setState({count:count+value*1})
    }
    decrement = () => {
        const {value} = this.selectNumber;
        const {count} = this.state;
        this.setState({count:count-value*1})

    }
    incrementIfOdd = () => {
        const {value} = this.selectNumber;
        const {count} = this.state;
        if(count%2 != 0){
            this.setState({count:count+value*1})
        }
    }
    incrementAsync = () => {
        const {value} = this.selectNumber;
        const {count} = this.state;
        setTimeout(() =>{
            this.setState({count:count+value*1})
        },500)
    }

    state = {
        count: 0

    }

    render() {
        return (
            <div>
                <h1>当前和为：{this.state.count}</h1>
                <select ref={c => this.selectNumber = c}>
                    <option value="1">1</option>
                    <option value="2">2</option>
                    <option value="3">3</option>
                </select>&nbsp;
                <button onClick={this.increment}>+</button>
                <button onClick={this.decrement}>-</button>
                <button onClick={this.incrementIfOdd}>和为奇数再加</button>
                <button onClick={this.incrementAsync}>异步加</button>
            </div>
        )
    }
}
